FOD2743C

OPTICALLY ISOLATED ERROR AMPLIFIER FOD2743A

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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2743A
DESCRIPTION
The FOD2743 Optically Isolated Amplifier consists of the popular KA431 precision programmable shunt reference and an optocoupler. The optocoupler is a gallium arsenide (GaAs) light emitting diode optically coupled to a silicon phototransistor. It comes in 3 grades of reference voltage tolerance 2%, 1%, and 0.5%. The Current Transfer Ratio (CTR) ranges from 50% to 100%. It also has an outstanding temperature coefficient of 50 ppm/ C. It is primarily intended for use as the error amplifier/ reference voltage/optocoupler function in isolated ac to dc power supplies and dc/dc converters. When using the FOD2743, power supply designers can reduce the component count and save space in tightly packaged designs. The tight tolerance reference eliminates the need for adjustments in many applications. The device comes in a 8-pin dip white package.
8 1 8 1 8 1

FOD2743B

FOD2743C

FEATURES
Optocoupler, precision reference and error amplifier in single package 2.5V reference CTR 50% to 100% at 1mA 5,000V RMS isolation UL approval E90700, Vol. 2 CSA approval 1296837 VDE approval pending BSI approval pending Low temperature coefficient 50 ppm/ C max FOD2743A: tolerance 0.5% FOD2743B: tolerance 1% FOD2743C: tolerance 2%
FUNCTIONAL BLOCK DIAGRAM

LED

8 NC

COMP

7 C

GND

6 E

5 NC

APPLICATIONS
Power supplies regulation DC to DC converters

PIN DEFINITIONS
Pin Number 1 2 3 4 5 6 7 8 Pin Name LED COMP GND FB NC E C NC Pin function description Anode LED. This pin is the input to the light emitting diode. Error Amplifier Compensation. This pin is the output of the error amplifier. Ground Voltage Feedback. This pin is the inverting input to the error amplifier Not connected Phototransistor Emitter Phototransistor Collector Not connected

The compensation network must be attached between pins 2 and 4.

2004 Fairchild Semiconductor Corporation

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4/8/04